Most conventional liquid crystal display panels include a pair of glass substrates, a liquid crystal layer provided between the substrates, electrodes provided on each glass substrate, and polarizing plates fixed to each glass substrate. In this type of liquid crystal display panel, light emitted from the backlight passes through the polarizing plates and liquid crystal layer to create an image on the screen that is recognized according to the contrast that appears on the screen. However, much of the light from the backlight is lost before it reaches the screen due to absorption and reflection, thereby reducing the light use efficiency of the display panel. Loss of light due to the polarizing plates accounts for a particularly large reduction in light use efficiency.
As a result, in recent years there has been increased development of light modulating devices, which are different from liquid crystal panels in that polarizing plates are not required (see Patent Documents 1 and 2, for example).
FIG. 23 shows cross-sectional views that illustrate the principle of operation of a light modulating device (optical device) disclosed in Patent Document 1. FIG. 23(a) is a cross-sectional view that shows the light absorbing state, and FIG. 23(b) is a cross-sectional view that shows the light reflecting state. The optical device disclosed in Patent Document 1 has a configuration in which polymer flakes are suspended in a liquid host (medium), and the optical characteristics of those flakes are selectively modified by changing the applied voltage.
When nematic liquid crystals are used as the liquid host, for example, applying an AC voltage to the optical device causes the liquid host to orient parallel to the electric field E, which in turn causes the flakes to orient in the liquid host alignment direction.
The configuration of this optical device removes the need for polarizing plates and can therefore increase light use efficiency in comparison with a liquid crystal panel.